Diving Deeper, discovering how the marine environment ticks!

Transcription

1 1 Diving Deeper Diving Deeper, discovering how the marine environment ticks! The Marine Environment Over 3,000 million years ago, life may have begun in the sea as simple bacteria. As ancient time progressed, there slowly evolved a diversity of soft-bodied invertebrates (2800 million years ago) followed by hard covered invertebrates (500 million years ago). Marine animals became more like the animals familiar to us today, land plants and animals began to evolve, as they became adapted to life out of water (400 million years ago). Armoured fish appeared, giant amphibians and reptiles ruled a diverse land environment, climates changed dramatically from tropical to ice age and back again. As recently as 2 million years ago, giant sharks inhabited our seas. Around this time Australia separated from Gondwana and became recognisable as the island continent. The evolution of life in the seas has its results in the plants and animal life we see today. The pattern of life and death, ebb and flow, evolution and extinction continues. All marine organisms, from the simple to the complex are affected by the constant changes to their environment - the daily tidal rhythms, the monthly lunar tide cycles, the day/night pattern, the seasonal ocean currents and weather patterns that shape the coasts and influence the seas. Coastlines battered and eroded by rough seas or built up by gentle sediment-laden water, slowly alter shape and form, producing a diversity of habitats. From the coastal fringes to the deepest trenches of the oceans a vast range of marine habitats support an astounding variety of coastal and marine plants and animals. They may be considered in two broad categories: Benthic and Pelagic. The Benthic Habitat This habitat covers the entire sea bed. All creatures that live on or in the sea bed or attached to the substrate make up what is known as the Benthos. The Pelagic Habitat This habitat includes the mass of waters above the benthic. Pelagic organisms can be divided into: Nekton The strong swimmers Plankton The weak swimmers or drifters Neuston Organisms that float on the surface of the sea e.g. by-the-wind sailors. Water Temperature Water temperature has a controlling influence on the kinds of marine life that is found in any part of the sea. Sea temperature range from 2 to 30 C. Marine biologists often describe general definitions of the oceans as: High latitude seas associated with polar regions Temperate seas such as those experienced in Southern Australia Tropical seas such as those in Northern Australia. Habitats On the fringes of the oceans are the beaches, the rocky shores, estuaries and bays, sea grass meadows, mud flats, salt marshes and mangroves. Extending back from the beaches is the buffer zone of cliffs, bluffs or dunes and behind this the catchment, which may include grasslands, farmland, woodland or increasingly large sections of urban development. Though each region has its own distinctive features, they remain interconnected and co-exist in a fragile state of balance, each to some degree affecting or being affected by what happens in the adjoining areas. Readily accessible coastal areas provide the opportunity to investigate habitats and the ecosystems that operate within them. For ease of reference some habitats are briefly described by the distinct features that characterise them on the following pages.

2 2 Diving Deeper HABITATS On the fringes of the oceans are the beaches, the rocky shores, estuaries and bays, sea grass meadows, mud fiats, salt marshes and mangroves. Extending back from the beaches is the buffer zone of cliffs, bluffs or dunes and behind this the catchment, which may include grasslands, farmland, woodland or increasingly large sections of urban development. Though each region has its own distinctive features, they remain interconnected and co-exist in a fragile state of balance, each to some degree affecting or being affected by what happens in the adjoining areas. Sand Dunes Sand blown landwards by prevailing onshore winds will gradually build up over time if trapped by vegetation. As the vegetation takes hold more sand accumulates and the area begins to stabilise. With the loss of vegetation, erosion and blowouts can occur. Readily accessible coastal areas provide the opportunity to investigate habitats and the eco-systems that operate within them. For ease of reference some habitats are briefly described by the distinct features that characterise them on the following pages. Rocky Shores This part of the shore can be very sheltered or exposed to high wave action. Marine life range from sparse to abundant. Because of the rise and fall of the tide, different organisms are able to live at different levels high up or low down on this shore, according to their ability to cope with such stresses as desiccation, temperature, wave action or predation. Sandy Beaches These habitats consist of constantly changing deposits of sand, which are built up and washed away by the action of waves, wind and currents. Many animal inhabitants are burrowers, that eat detritus/rotting material or one another and in turn are preyed on by visiting sea birds.

3 3 Diving Deeper Coral Reefs Because of the amazing abundance and variety of organisms on these reefs, they are sometimes compared with their terrestrial counterparts, the tropical rainforests. The reefs)re formed from the exoskeletons of myriads of polyps, in warm seas of between 18 C and 25 C They are therefore generally limited to a zone approximately 21.5 North and South of the equator. The most famous of these reefs is the Great Barrier Reef off the east coast of Queensland. Rockpools Pockets of water left by a receding tide house a great diversity of sea life and are easily investigated at low tide. Producers (plants) and consumers (herbivores and carnivores), predators and their prey are all part of this miniature world. Ocean Bed This is the soft bottom area of the sea that can range from coarse sand to muddy 'oozes'. Animals living here usually rest on the substrate or bury themselves in the sediment. Many feed on detritus (dead plant and animal matter that drifts down from above). Open Ocean This zone is by far the largest of all marine environments. It extends from surface water to sea bed and from shore to shore. A variety of marine organisms inhabit different levels at varying depths in this environment. Kelp Beds These 'forests of the sea' can be found in cool waters where there are rocks on which the plant can become firmly attached and grow towards the light. Plants and animals live here in abundance. Like forests on the land, these places provide food and shelter for a wide range of organisms.

4 4 Diving Deeper Sea Grass Meadows These 'pastures of the sea' provide food, shelter, breeding grounds and nursery areas for many marine organisms including fish. They are found in shallow waters of 2-12 m depth where sufficient light penetrates for photosynthesis to take place. Mud Flats These quiet, shallow soft-sediment areas receive water run off from the land and gentle tides from the sea. They provide a nursery area for marine life and are a favourite habitat for worms, molluscs, crabs and many water birds, including migratory waders. Mangroves These trees are adapted to a habitat subject to frequent inundation by salt water. Their roots are multi-functional in that they slow down currents, trap sediments and provide a base to which many organisms attach themselves. They perform the important function of filtering and purifying land-based water run off. Mangroves are also a vitally important nursery habitat for many animals. Estuaries Variations in the flow of tides from the sea and fresh water from the land restricts the range of plants and animals able to cope with these conditions. The soft substrates of sand and mud are a habitat for worms molluscs and crustaceans. Prawns, juvenile fish and water birds are attracted by the food and shelter these areas provide.

5 5 Diving Deeper Scientists at work! Plankton means to drift. Plankton is the name given to plants and animals in the sea that drift around the ocean. Plankton are mostly tiny or microscopic. Put the following words into the right place! Plankton, phytoplankton, zooplankton, microscopic, drifting, mega plankton, oxygen Plankton means in the ocean, without being able to choose which way to swim. Tiny marine plants and animals are called The tiny animal plankton in our ocean are called Zooplankton range in size from microscopic to such as huge sea jellies. Phytoplankton provide an estimate 80% of the world s supply! Who am I? Almost all animals in the sea depend in some way on plankton for food! Can you guess what zooplankton will grow into? Did you know Every time you swallow a mouthful of seawater when you are swimming, you would have swallowed millions of tiny phytoplankton and zooplankton.

6 6 Diving Deeper Undersea view What to do Step 1 Step 2 Step 3 Step 4 Step 5 Step 6 Step 7 Step 8 Step 9 Cut out the front of the box (the part where the tissues pull through). Cut out two holes big enough for your eyes at the back of the box. Line the box with silver foil, coloured paper or cellophane (leave the eye holes clear). Cut out pictures of sea creatures from old magazines or make sea creatures and seaweeds from coloured paper e.g. turtles, fish, sea stars, sea urchins, dolphins, octopus, cuttles, crabs. Use your imagination. Hang these from the top of your box by tying a piece of string through your sea like then through the top of the box. Decorate the bottom with sand or shells. Decorate the outside of your box with coloured paper. Cover the open front of the viewer with a piece of blue cellophane to enclose the scene. Hold the viewer up to the light! When you look through the box you will view an amazing underwater world full of life.

7 7 Diving Deeper dapted for survival Sea creatures have special adaptions to help them survive in their environment. Some of these adaptions enable them to get their food, some help them to hide from predators and some can stop their bodies from drying out when they are not covered in water. Using the five creatures on this page, label the parts of their body that enable them to survive in their habitat. There will be more than one for each Leafy sea dragon Fish Snail Sea urchin Hermit crab

8 8 Diving Deeper Survival in the sea 1,000 A. B. C. D. E. F. A fish has just laid 1000 eggs in the sea. A. Half of these were eaten by fish B. A person fishing pulled up an anchor with lots of seaweed and 62 of the fish eggs were washed away. C. During a huge storm 38 fish eggs were washed ashore D. Of the remaining eggs one quarter of these were blown into a rockpool which dried out in the sun. E. Once the remaining eggs hatched into small fish 42 were eaten by bigger fish. F. They grew into medium size fish but one third were eaten by seals. G. Half of all the remaining fish were caught on fishing lines and eaten by people. 1. How many fully grown fish from the initial 1000 eggs laid were left to survive and reproduce in the sea? Total survived G. 2. Why is it important for some sea creatures to have many eggs? 3. What might happen to a species like this fish if she only released a few eggs?

9 9 Diving Deeper How do they eat? Use reference books and the Internet to find out how these animals get their food. How does a sponge get its food? How does a sea anemone get its food? How does a sea star get its food? How does a seahorse get its food? How do you get your food?

10 10 Diving Deeper Snails that hid from the sun! When you are at the beach look in the shallow water or rockpools. Search for some live sea snails. Materials Magnifying lens Cup or small bucket Step 1: Collect a couple of them in your cup or bucket. Be gentle when removing them off the rocks or seaweed. Step 2: Place the snail on a flat part of the beach. What do they do? Step 3: Examine the opening of the shell with a magnifying lens. What has happened? Step 4: Try putting some cool seawater on your hand and placing the snail on it. What happens? Step 5: Don t leave them in the sun; put your sea snails back where you found them. Sea snails need to avoid drying out. Sea snails have a trap door that seals moisture inside their shell and protects their soft body parts.

11 11 Diving Deeper Word-out postcard! This is best done when students have some background knowledge about the threats to the marine environment. Begin with a focus discussion as a class: How would they describe the ocean to someone who has never seen it? What is their favourite sea creature? What do they think is special about the ocean? Share with them the idea that they can make a difference by spreading the word about what they have learned about the ocean and how to protect it. Based on the discussion, have each student decide on one aspect that they would like to share with someone else using their word-out postcard. Brainstorm a list of potential people they can send their word-out card to. (Councils, premier, prime minister, relatives etc.) Step 1: Have the students write a draft of what they want to write and check it before the students write on the actual postcard. Step 2: Have the students draw a picture of their message on the front of the postcard. Encourage students to be creative and help show off their special message. Step 3: When the students have finished, either mail the postcards as a group or allow them to hand deliver them. Allow students to exhibit their post cards before sending them. Materials Scissors White card cut to the postcard size Decorating materials paints, scrap paper, pencils or colouring pens

12 12 Diving Deeper Pollution solutions List 10 types of pollution that can harm sea creatures. Write a sentence about how this type of pollution might harm sea creatures. List some ways that you can think of that we can make sure our litter and pollution does not harm the sea creatures in their homes. How long? You guess! Rubbish that goes into the sea can often still be around for many years to come. Fill in the table below as to how long you think each item might take to break down in the sea. Your guess on how long? (Ask your teacher to find the answers on the next page.) Paper Orange Milk Nylon Glass Cigarette Plastic Steel card peel carton butts can

13 13 Diving Deeper Connected to the sea Have the students work in small groups with large sheets of butcher paper to write on. Ask students to write down on the paper all the ways that they can think of that people are connected to the sea. Discuss the ides as a class writing them onto the board. (Food, products, pleasure, work, pollution, transport etc.) Reduce this list down to how the students themselves think they personally are connected to the sea e.g. what products from the sea do they use at home? If they visit the sea, what do they do while they are there? What kind of impact do they have during their visit? (Boating, exploring over the rocks, squishing rock pool creatures, dogs chasing birds or collecting shells.) What happens to the water that goes down the drains at home? Why are those who live far away from the sea still connected in many ways? Answers to Pollution solutions Paper card 2-4 weeks Orange peel up to 2 years Milk carton 5 years Nylon years Glass Indefinetly Cigarette butts 1 5 years Plastic years Steel can years.

14 14 Diving Deeper Get involved Find out what organisations are involved in protecting sea plants and animals Write letters to those organisations to find out how you can protect whales, other sea mammals, birds and other sea creatures at risk. Get your school to join these organisations as they rely on membership income and volunteers to reply to your letters. Share the information you found out about how people can help protect the sea and its creatures. As a class make up a contact directory list of all the groups, people and organisations you found and include a brief description about what they do to help protect the sea. Write a letter to some of these contacts to find out more about what people can do to help. Visit a web site Sea for yourself /coastcare

15 15 Diving Deeper Pollution monitoring Who monitors your pollution problems? Find out which organisations help to monitor and prevent pollution in your area. See if you can help out with some pollution problems. Divide the class into smaller groups to research one of the following case studies. Have the students report their findings back to the class. Make a brochure of the contacts. Distribute these to your local community. Case study one You head down to the beach for the day with two friends. You notice that a huge pile of rubbish has been dumped right in the middle of the beach. Most of the rubbish is plastic but you also notice old paint tins and a petrol can. There is too much rubbish for you to remove in a bag and there may be some dangerous items in there. Who will you contact? What will they do? What will happen to the rubbish? Case study two It s low tide and you head to the beach for a swim. Your favourite place is the rocks near cool water. As you head out over the rocks you notice all the rocks are covered in a slippery black oil. You look into the water and notice the water has a layer of oil covering it. You can see some ships out in the water but are not sure if they have anything to do with the problem? Who will you contact? What will they do? Who else will be involved? How can you help? Case study three The storm has settled and you head to the beach for a walk. A huge stormwater drain is gushing out rain water and rubbish into the ocean. Not far from here you notice huge numbers of dead fish washed onto the beach and many almost half dead in the water. Who will you contact? What will they do? Who else will be involved? Is there anything you can do?